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From:   Yizhuo <yzhai003@ucr.edu>
Cc:     Yizhuo <yzhai003@ucr.edu>, Mark Fasheh <mark@fasheh.com>,
        Joel Becker <jlbec@evilplan.org>,
        Joseph Qi <joseph.qi@linux.alibaba.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        ChenGang <cg.chen@huawei.com>,
        Richard Fontana <rfontana@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Jia Guo <guojia12@huawei.com>, ocfs2-devel@oss.oracle.com,
        linux-kernel@vger.kernel.org
Subject: [PATCH] ocfs2:fix potential Null Ptr Dereference
Date:   Wed,  9 Oct 2019 18:07:50 -0700
Message-Id: <20191010010752.25941-1-yzhai003@ucr.edu>
To:     unlisted-recipients:; (no To-header on input)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Inside function o2hb_region_blocks_store(), to_o2hb_region()
could return NULL but there's no check before its dereference,
which is potentially unsafe.

Signed-off-by: Yizhuo <yzhai003@ucr.edu>
---
 fs/ocfs2/cluster/heartbeat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index a368350d4c27..93f2b540f245 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -1628,7 +1628,7 @@ static ssize_t o2hb_region_blocks_store(struct config_item *item,
 	unsigned long tmp;
 	char *p = (char *)page;
 
-	if (reg->hr_bdev)
+	if (!reg || reg->hr_bdev)
 		return -EINVAL;
 
 	tmp = simple_strtoul(p, &p, 0);
-- 
2.17.1